Reflector for providing uniform light energy

ABSTRACT

Systems are disclosed for providing ultraviolet (UV) energy to items on a processing surface. The system includes a lamp positioned over the processing surface to provide UV energy to the processing surface and a reflector cell positioned to cause UV energy emitted from the lamp in a direction away from the processing surface to be reflected toward the processing surface. The system includes the reflector cell having a reflector cap positioned above the lamp and a shroud extending downwardly from the reflector cap toward the conveyor wherein the shroud has a vertical dimension, a longitudinal dimension, and a horizontal dimension along the direction of the conveyor such that the horizontal dimension and the longitudinal dimension define a treatment area on the conveyor. The lamp is configured to deliver energy to the treatment area such that the delivered energy to the processing surface is substantially uniform over the treatment area.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.62/667,136, filed May 4, 2018, entitled “Reflector for Providing UniformLight Energy,” the contents of which are incorporated herein in theirentirety.

TECHNICAL FIELD

The present disclosure relates generally to light systems, and inparticular, to systems and methods for providing uniform UV light to asurface area.

BACKGROUND

In some systems for providing UV light to a target item, a UV lamp ishoused in an envelope and emits UV light that is provided to items to betreated, in some cases through a UV-transparent fused silica window,often referred to as quartz. In one type of system, a conveyor beltbrings items to be radiated to a xenon flash lamp system, and one ormore flash lamps provides one or more flashes of broadband light to theitems to be treated. The UV treatment can be used for differentpurposes, such as curing an adhesive, annealing, or deactivatingmicroorganisms.

SUMMARY OF THE INVENTION

The present disclosure includes a system for providing ultraviolet (UV)energy to items on a processing surface that includes a lamp positionedover the processing surface to provide UV energy to the processingsurface and a reflector cell positioned to cause UV energy emitted fromthe lamp in a direction away from the processing surface to be reflectedtoward the processing surface. In some embodiments, the reflector cellincludes a reflector cap positioned above the lamp and a shroudextending downwardly from the reflector cap toward the conveyor. In someembodiments, the shroud has a vertical dimension, a longitudinaldimension, and a horizontal dimension along the direction of theconveyor whereby the horizontal dimension and the longitudinal dimensiondefining a treatment area on the conveyor. In some embodiments, the lampis configured to deliver energy to the treatment area and the reflectorcap, and the shroud are configured such that the delivered energy to theprocessing surface is substantially uniform over the treatment area.

In some embodiments, the system's lamp includes at least one flash lampand the energy in the treatment area is substantially uniform to within5%. In some embodiments of the system, the processing surface is definedby a conveyor. In some embodiments, the reflector cap and the shrouddefine and enclose a treatment volume. In some embodiments, thereflector cap and the shroud have a reflective material along theirrespective interior surfaces facing the treatment area. In someembodiments, the reflector cap includes a first panel and a secondpanel, and the first panel and the second panel extend upwardly awayfrom the processing surface and at about a positive and negative 45degree angle, respectively, relative to the processing surface. In someembodiments, the first and second panels intersect above the lamp suchthat an angle between the first panel and the second panel isapproximately 90 degrees. In some embodiments, the lamp includes a firstlamp and a second lamp spaced apart, wherein the first and second panelsextend over the first lamp. In some embodiments, the system furtherincludes a third panel and a fourth panel whereby the third panel andthe fourth panel extend upwardly away from the processing surface and atabout a positive and negative 45 degree angle, respectively, relative tothe processing surface. In some embodiments, the third and fourth panelsintersect above the second lamp such that an angle between the thirdpanel and the fourth panel is approximately 90 degrees.

In some embodiments of the system, the reflector cap includes a firstelliptical shape defining a portion of a first ellipse with a major axisalong a first line parallel to the processing surface and perpendicularto a second line from the lamp to the processing surface. In someembodiments, the lamp is positioned at a first focus of the ellipse, anda second focus of the ellipse being spaced from the first focus alongthe first line. In some embodiments, the reflector cap includes a secondelliptical shape defining a portion of a second ellipse with a majoraxis along the first line whereby the second ellipse has a first focusco-located with the first focus of the first ellipse, and a second focusof the ellipse being spaced from the first focus and from the secondfocus of the first ellipse along the first line. In some embodiments,the reflector cap includes an elliptical portion defining an ellipsehaving a major axis perpendicular to the processing surface. In someembodiments, the lamp is positioned at a first focus of the ellipse, andthe system includes a second focus below the first focus such that theshroud has a parabolic shape with a focus co-located with the secondfocus of the reflector cap. In some embodiments, the system furtherincludes a UV-transmissive window positioned between the lamp and theprocessing surface.

In some embodiments, the system includes at least one ultraviolet (UV)energy lamp positioned above a processing surface, wherein the plane ofthe processing surface defines a first direction, and the direction fromthe lamp to the conveyor is a second direction perpendicular to thefirst direction. In some embodiments, the system includes a reflectorcell positioned to cause UV energy emitted from the lamp in a directionaway from the processing surface to be reflected toward the processingsurface. In some embodiments, the reflector cell includes a reflectorcap positioned above the flash lamp and away from the processing surfacewhere the reflector cap has first and second planar panels that extendaway from the processing surface at an angle relative to the seconddirection and meet at a location above the lamp and form a V-shapedcross section. In some embodiments, the system includes a shroud havingat least a third panel extending downwardly from the first panel towardthe conveyor, and a fourth panel extending toward the processing surfaceand parallel to the third side such that the lamp provides energy to theprocessing surface in a treatment area below the first and second sidesand bounded by the third and fourth panels.

In some embodiments, the lamp includes a flash lamp. In someembodiments, the reflector cap and the shroud define a treatment volumeand the reflector cap and the shroud include a reflective material alonginterior surfaces facing the treatment volume. In some embodiments, thefirst and second panels intersect such that the V-shape is approximately90 degrees. In some embodiments, the processing surface includes aconveyor and the system further includes a UV-transmissive windowpositioned between the lamp and the conveyor. In some embodiments, thesystem includes a second lamp and a second reflector cap having fifthand sixth planar panels that that extend away from the processingsurface at an angle relative to the second direction and meet at alocation above the lamp and form a second V-shaped cross section. Insome embodiments, the fourth panel extends downwardly from the secondpanel, such that the first, second, third, and fourth panels define ahome plate shape in cross-section.

In some embodiments, the system includes at least one ultraviolet (UV)energy lamp positioned above a planar processing surface, wherein adirection from the lamp to the processing surface is a first directionperpendicular to the processing surface. In some embodiments, the systemincludes a reflector cell positioned to cause UV energy emitted from thelamp in a direction away from the processing surface to be reflectedtoward the processing surface. In other embodiments, the reflector cellincludes a reflector cap positioned above the flash lamp and away fromthe processing surface, wherein the reflector cap includes a firstelliptical portion that defines a first elliptical shape with a majoraxis parallel to the processing surface and perpendicular to the firstdirection. In some embodiments, the lamp is located at one focus of thefirst elliptical shape, and a second focus of the first elliptical shapeis spaced from the first focus along the second direction. In someembodiments, the system includes a shroud extending from the reflectorcap toward the processing surface.

In some embodiments, the system includes a second elliptical portionthat defines a second elliptical shape having a major axis co-linearwith the major axis of the first elliptical shape. In some embodiments,the lamp is located at a first focus of the second elliptical shape, anda second focus of the second elliptical shape is spaced from both fociof the first elliptical shape. In some embodiments, the shroud includesfirst and second panels that are spaced apart and extend from thereflector cap toward the processing surface. In some embodiments, thespacing of the first and second panels defines a dimension of atreatment area for the UV energy.

These and other capabilities of the disclosed subject matter will bemore fully understood after a review of the following figures, detaileddescription, and claims. It is to be understood that the phraseology andterminology employed herein are for the purpose of description andshould not be regarded as limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system diagram of a system for treating items using a flashlamp system with a UV-transmissive window, according to some embodimentsof the present disclosure.

FIG. 2 is a plan view of a system for treating circuit components usinga single-cell flash lamp system, according to some embodiments of thepresent disclosure.

FIG. 3a is a side view of a system for treating items using a flash lampsystem with a flash lamp reflector cell having an elliptical reflectorcap, according to some embodiments of the present disclosure.

FIG. 3b is a side view of a system for treating items using a flash lampsystem with a flash lamp reflector cells made of multiple ellipticalportions, according to some embodiments of the present disclosure.

FIG. 4 is a side view of a system for treating items using a flash lampsystem with a single angular flash lamp reflector cell, according tosome embodiments of the present disclosure.

FIG. 5 is a top view of a system for treating items using a flash lampsystem with a singular flash lamp angular reflector cell, according tosome embodiments of the present disclosure.

FIG. 6 is a side view of a system for treating items using a flash lampsystem with multiple angular flash lamp reflector cells, according tosome embodiments of the present disclosure.

FIG. 7 is a side view of a system for treating items using a flash lampsystem with multiple, overlapping circular segment reflector cells,according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

In some applications of UV energy, e.g., sintering traces of conductivelines with nanoparticles, it can be useful to have a large coverage areawith known uniform energy being delivered. The systems and methodsdescribed here are for reflector systems that provide substantiallyuniform UV energy over a large area. As used herein, both “UV energy”and “light” are used to describe the output of a lamp system in varyingembodiments of the present disclosure.

The system is described here in the context of a UV flash lamp system,such as systems provided by Xenon Corporation, Wilmington Mass., butcould be used in a continuous light UV system with one or more mercurylamps, or in other types of light systems.

Such systems often have a reflector positioned such that the lightsource is between the reflector and the items to be treated. Thereflector directs UV light energy toward the items to be treated. Somereflector configurations are known, such as a circular shape; atrapezoidal hood; a parabola with the lamp positioned at the focus ofthe parabola; an elliptical orientation where the lamp is positioned atone focus and the target area is at another focus (i.e., the major axisis vertical); and reflectors with ridges directly behind the lamp.Examples of prior reflectors are shown, for example, in U.S. Pat. Nos.4,264,947 and 6,030,086.

FIG. 1 is a system diagram of a system for treating items using a flashlamp system with a UV-transmissive window, according to some embodimentsof the present disclosure. FIG. 1 shows a UV system 10 with a UV flashlamp 12 coupled to a control system 16, a reflector 18, aUV-transmissive window 20, items 22, and a conveyor 23. Control system16 controls, for example, the operation of UV flash lamp 12 includingthe frequency at which UV flash lamp 12 pulses per unit time and theintensity at which UV flash lamp 12 pulses. In some embodiments,reflector 18 surrounds a portion of UV flash lamp 12 to help direct thelight output from UV flash lamp 12 in a desired direction throughUV-transmissive window 20, the main portion of which is made of fusedsilica. The light output from UV flash lamp 12 passes throughUV-transmissive window 20 to items 22 that are treated by the lightoutput. Items 22 can be provided on conveyor belt 23, which can bestopped periodically during treatment or move continuously.

In some embodiments, items 22 may be optical memory disks with anadhesive that needs to be cured or items with a surface treatment thatneeds to be cured or annealed. Items 22 may also be food to bedisinfected (as UV with wavelengths in the UV-C range are known todamage the DNA of pathogens), or a substrate with traces of a conductiveink with nanoparticles to be sintered to produce electrical circuits.This last example, of sintering a substrate with a conductive ink, willbe used for purposes of description. In this case, the substrate can bemade of a plastic film, or paper, or some other non-conductive material.Patterns of lines of conductive ink are formed on the substrate tocreate circuit paths. The substrate can be in individual pieces, asshown as items 22 in FIG. 1, or can be a continuous roll such thatcircuits are formed in a continuous substrate and separated using alater process.

FIG. 2 is a plan view of a system for treating circuit components usinga single-cell flash lamp system, according to some embodiments of thepresent disclosure. FIG. 2 shows a lamp system including an elongatedcylindrical flash lamp 30 and a substrate 32 with conductive electronictraces 34 and 36. A reflector, as described later herein, may often beused with the lamp system of FIG. 2, but is not shown here. Substrate 32is shown moving in a direction from the left towards the right side ofFIG. 2 and may be moved in that direction by a conveyor (not shown). Thelocation of substrate 32 occupies a treatment area of the system and maybe moved into and out of the treatment area manually by an operator,automatically by a conveyor, or by other processing means. Conductiveelectronic traces 34 and 36 may be made from a conductive ink withnanoparticles. As substrate 32 is moved left to right, either in astop-and-start or a continuous manner, flash lamp 30 may flash a UVenergy output at a set frequency (e.g., 3 flashes per second) and a setpulse duration (e.g., on the order of microseconds to milliseconds) asdetermined by an operator or a control system (not shown). In someembodiments, flash lamp 30 has a diameter “d” and a length “1”. Inembodiments of the system like that displayed in FIG. 2, there may benon-uniformities in the UV energy output, and therefore the energydelivered to substrate 32 can include higher and lower intensity areaswithin the total treatment area. Flash lamp 30 may produce a specificfootprint of UV energy output onto substrate 32, made up of an areahaving width slightly larger than distance “d.” Because of thedispersing nature of light produced from a single source, the intensityof light at the surface will have a peak intensity within the footprintof the flash lamp and that intensity will fall off towards zero quicklyat locations further outside of the footprint. The UV energy outputenergy from lamp 30 sinters the ink used to create electronic traces 34and 36 and fuses the particles. Sintering causes an increase in thepre-sintered conductivity of the electronic traces 34 and 36, asdescribed in U.S. Patent Application Publication No. 2003/148024. Inplace of the circuit elements shown, the system in FIG. 2 may also beused for photographic processing, curing applications, or otherapplications where UV energy is applied to an item over large areas oftreatment.

In some iterations of the system shown in FIG. 2, the system may havemultiple lamps arranged in a row or in a two-dimensional array. Eachlamp can be circular, elongated, spiral, or some other desired shape.The process of causing the lamp to flash for a desired duration, with adesired pulse frequency, is generally well known. The UV energy from abare lamp, however, falls off rapidly as one moves away from points onthe illuminated plane, described as the footprint of the lamp above, atminimum distance from the lamp. Small areas of uniformity exist insystems using multiple lamps, but the area of uniform UV energy outputdoes not occupy an area that is much larger than the surface area of thelamps itself (e.g. outside of the footprint). For example, in the caseof a cylindrical, elongated linear bulb with diameter “d” and length“1,” the two-dimensional area of the bulb would be represented as l×d.In embodiments of the system described below, the area of uniform UVenergy output is much larger than l×d, and is at least 10 times thatarea, or 10×l×w, or it may be more than 15, or 20, or 25 times the areaof flash lamp 30. In the case of a cylindrical lamp with a diameter of 8mm, the coverage area would be at least the length of the lamp, l×80 mmfor a 10× coverage area; or for a 20× coverage area, l×160 mm. By use ofsuitable UV energy redirecting designs, as disclosed herein andexplained in more detail with regard to FIGS. 3-6, the illuminationacross a larger defined area can be made uniform. In some embodiments,this is achieved by only using reflecting surfaces. Exclusive use ofreflective surfaces minimizes the amount of output from a flash lamplost to absorption or Fresnel reflection from any refractive medium usedand is not susceptible to dispersion of colors due to varying refractiveindex with wavelength.

In some embodiments, the uniformity of UV energy incident upon a treateditem, such as the circuit components 34, 36, should be such that theenergy has not more than about a 5% variation throughout the coveragearea. In other embodiments, the desired variation of an operator mayrange between about 2% and 10% variation, depending on the intendedapplication or use. Variation across the coverage area may, for example,be measured as the comparison between the average illumination intensityacross the entire treatment area and the average illumination intensityas measured at discrete sub-units of the treatment area. This uniformitycan be measured, for example, with cyanotype paper that turns shades ofblue in response to the UV flashes. The sheets can be scanned todetermine the level of uniformity. The uniformity from the lamp systemmay also be measured using other indicator paper products or using areadetectors to determine the intensity of incident UV light upon thetreatment area.

FIG. 3a is a side view of a system for treating items using a flash lampsystem with a flash lamp reflector cell having an elliptical reflectorcap, according to some embodiments of the present disclosure. FIG. 3ashows a flash lamp 39 and a reflector cell 41 positioned over a conveyor49. Reflector cell 41 includes an elliptical reflector cap 43 and shroudwalls 45, 47 (also referred to herein as “components” of reflector cell41). Conveyor 49 has a width (not shown) that extends along the plane ofthe conveyor 49 into FIG. 3a such that distance 51 between shroud walls45 and 47 defines a coverage area quantified as the width of conveyor 49times the distance 51. Conveyor 49 may be configured to transport itemsand may be replaced by other processing means including, for example,manual movement by an operator. Reflector cell 41 may also includeadditional shroud walls, such as walls perpendicular to walls 45 and 47(not shown) that completely enclose the coverage area of conveyor 49over distance 51. Reflector cell 41 may include shroud walls have ahorizontal dimension, measured in the same direction as distance 51, avertical dimension, measured between conveyor 49 and flash lamp 39, anda longitudinal dimension, measured along the same longitudinal axis offlash lamp 39 (e.g. into the page as depicted in FIG. 3a ). In someembodiments, the longitudinal dimension of reflector cell 41 may be thesame distance as the width of conveyor 49. Shroud walls 45 and 47 are oneither side of the coverage area and extend downward and substantiallyperpendicular to the conveyor 49. Shroud walls 45 and 47 may extend mostof the way to the conveyor 49 such that minimal space exists betweenshroud walls 45, 47 and conveyor 49. At least one of the benefits ofthis configuration is that minimal light from the environment may enterthe internal space of reflector cell 41, allowing for precise deliveryof UV energy output from flash lamp 39 to the surface of conveyor 49 oritems treated thereon. In some embodiments, reflector cell 41 mayinclude a window (not shown) between flash lamp 39 and conveyor 49,similar to that described above with respect to FIG. 1

In FIG. 3a , elliptical reflector cap 43 is a portion of an ellipse thatextends from shroud wall 45 over flash lamp 39 to shroud wall 47. Theellipse corresponding to elliptical reflector cap 43 has two foci: f1,which is a location, but not a physical item, where flash lamp 38 may beplaced, and a second focus f2. The major axis created by the locationsof the two foci is perpendicular to a line from the flash lamp 39 to theitems being treated, e.g., horizontal in the depicted orientation. Flashlamp 39 is placed at focus f1 so that the UV energy output from flashlamp 39 reflects from the elliptical reflector cap 43 and appears atconveyor 49 as if the UV energy output is emanating from one of twovirtual sources, lying in distinct planes above the true source, inaddition to the light output physically emanating from flash lamp 39itself. A first virtual source 51 will result from the reflection offlash lamp 39 in elliptical reflector cap 43 at a location sufficientlyclose to above the first focal point f1. A second virtual source 53 willresult from the reflection of the flash lamp 39 in elliptical reflectorcap 43 at a location sufficiently close to above the second focal pointf2. The effect is to make each individual UV energy source, e.g. flashlamp 39, behave as if three separate UV energy sources, although two ofthe virtual sources lie in one plane somewhat farther from theilluminated plane, while the third literal source lies at the firstfocal point f1. Flash lamp 39 may also be placed at focal point f2,wherein the virtual images described above would reverse orientationbetween their locations above the first and second focal points, f1 andf2.

FIG. 3b is a side view of a system for treating items using a flash lampsystem with a flash lamp reflector cell made of multiple ellipticalportions, according to some embodiments of the present disclosure. FIG.3b shows a flash lamp 38, and a reflector 40 cell positioned over aconveyor 50. Reflector cell 40 includes shroud walls 42 and 44 as wellas elliptical reflector caps 46 and 48 (also referred to herein as“components” of reflector cell 40). Conveyor 50 has a width (not shown)that extends along the plane into FIG. 3b such that a distance 52between shroud walls 42 and 44 defines a coverage area quantified as thewidth of conveyor 50 times the distance 52. Conveyor 50 is configured totransport items (not shown). Other processing means may be used in placeof conveyor 50 including moving items manually by an operator or byother processing means. Reflector cell 40 may also include additionalshroud walls (not shown) that completely enclose the coverage area ofconveyor 50 over distance 52. Reflector cell 40 may include shroud wallshaving a horizontal dimension, measured in the same direction asdistance 52, a vertical dimension, measured between conveyor 50 andflash lamp 38, and a longitudinal dimension, measured along the samelongitudinal axis of flash lamp 38 (e.g., into the page as depicted inFIG. 3b ). In some embodiments, the longitudinal dimension of reflectorcell 40 may be the same distance as the width of conveyor 50. Shroudwalls 42 and 46 are on either side of the coverage area and extenddownward and substantially perpendicular to the conveyor 50. Shroudwalls 42 and 46 may extend most of the way to the conveyor 50 such thatminimal space exists between shroud walls 42, 46 and conveyor 50. One ofthe benefits of this configuration is that minimal light from theenvironment may enter the internal space of reflector cell 40, allowingfor precise delivery of UV energy output from flash lamp 38 to thesurface of conveyor 50 or items treated thereon.

In some embodiments, the shroud walls 42 and 46 are planar walls made ofsubstantially nearly perfect specular mirrors, with very highreflectivity and with substantially planar and mechanically stablewalls. Due to the distance between the flash lamp 38 and the conveyor50, the UV energy output intensity will decrease while it propagatesfrom the flash lamp 38 and is also affected by the increasing number ofreflections. However, by that time the UV energy output appears to becoming from ever more distant virtual lamps behaving as a homogenoussheet of light output incident on a treatment area. In some embodiments,the components of reflector cell 40 may be constructed using a singlepiece of material. In other embodiments, the components of reflectorcell 40 may be coupled using clips, buckles, brackets, screws, or otherfasteners. In some embodiments, reflector cell 40 may include a window(not shown) between flash lamp 38 and conveyor 50, similar to thatdescribed above with respect to FIG. 1

Elliptical reflector caps 46 and 48 are each portions of differentellipses. Elliptical reflector cap 46 is a portion of an ellipse thatextends from point 54 directly above flash lamp 38 to point 56 where itmeets the shroud wall 42. The ellipse corresponding to ellipticalreflector cap 46 has two foci: f1, which is a location, but not aphysical item, and a second f2 where flash lamp 38 may be placed. Amajor axis created by the locations of the two foci is perpendicular toa line from the flash lamp 38 to the items being treated. Ellipticalreflector cap 48 is a portion of an ellipse that extends from point 54directly above flash lamp 38 to point 58 where elliptical reflector cap48 couples to shroud wall 44. The ellipse corresponding to ellipticalreflector cap 48 has two foci, the first of which is found at locationf2 in a concurrent location with that formed by flash lamp 38 andelliptical reflector cap 46 focus f2. The second focus of ellipticalreflector cap 48 is found at f3, which is another non-physical location.The distance between f1 and f2 is equal to the distance between f2 andf3, and as shown, foci f1, f2, and f3 are oriented perpendicular to thedirection from lamp 38 to the items to be treated.

In some embodiments, the elliptical reflector caps 46, 48 redirect theUV energy output emitted from flash lamp 38, which requires one or morereflections before it illuminates the treatment area defined by distance52 on conveyor 50. In this way, the UV energy output “fills in” theplaces where the illumination from the UV energy output of flash lamp 30is below a necessary threshold for treating items. Additionally, thecomponents of reflector cell 40 illuminate conveyor 50 withoutmaterially saturating places that are already sufficiently covered bythe direct illumination from flash lamp 38 and do so in such a way thatthe variations in illumination are precisely compensated for. Theuniform illumination of a treatment surface is supported by theunderstanding that, from a sufficiently great distance, UV energy outputfrom a single source may appear as a uniform distribution of UV energydetection at that location sufficiently far away. There may be smallvariations in the illumination along a direction perpendicular to thelongitudinal axes of the sources, but with increasing distance,anomalies in UV energy distribution decrease rapidly until they aresufficiently small and do not affect the application to a treatmentarea, described in detail below. In some embodiments, the reflector cellfunctions such that a single or finite number of lamps appear at theilluminated plane as if provided by an infinitely wide array ofequally-spaced, infinitely long UV energy sources.

In some embodiments, reflector cell 40 produces a treatment area that isat least a factor of 10 larger than the surface area of the flash lamp,as described above. Additionally, the treatment area canvassed byreflector cell 40 is substantially uniform. The reflections in thesystem produce the appearance of an infinite number of UV energysources. Multiple reflector cells 40 may be used in conjunction to treatan area having a total width equal to the sum of each individualreflector cell's 40 width.

In some embodiments, the reflector can be manufactured in one of anumber of ways, e.g., with a highly reflective sheet metal, or it can beformed by starting with a block of material from which material isremoved to form the contours, or 3D printing techniques can be used.

FIG. 4 is a side view of a system for treating items using a flash lampsystem with a flash lamp angular reflector cell, according to someembodiments. FIG. 4 shows an angular reflector cell 60 that includes aflash lamp 70, angular reflector cap 82, shroud walls 72 and 74, and aprocessing surface 88. Processing surface 88 may comprise a conveyor, asdescribed above in FIGS. 1-3. Angular reflector top 82 includes upperangled pieces 76 and 78 that extend upwardly at an angle relative to thevertical direction and meet at an angle 84 above flash lamp 70. Thisforms a V-shaped cross-section. In some embodiments, the angle 84 of theV-shape between upper angled pieces 76 and 78 is a right angle. Thereflector cap and shroud, along with the conveyor, generally trace out a“home plate” shape in cross section. Flash lamp 70 has a verticalposition 86 that is above a line 80 between the tops of the shroud walls72, 74. In some embodiments, a window (not shown) may be placed alongwith line 80, similar to that described above with regard to FIG. 1. Insome embodiments, the angled reflector cell 60 may include additionalshroud components (not shown) such that an area exists within the angledreflector cell 60 that is enclosed on five sides, with an opening overprocessing surface 88. In some embodiments, the angular reflector cellmay include a window (not shown) similar to that described above withrespect to FIG. 1

In some embodiments, the configuration of the angled reflector cellprovides the virtual appearance as if UV energy output from flash lamp70 originates from multiple UV energy sources and multiple distancesfrom items (not shown) being treated on a processing surface 88 by UVenergy output from flash lamp 70. A second distance between the flashlamp 70 and the portions of angular reflector cap 82, as well as thewidths of the portions of angular reflector cap 82 are chosen so thatthe UV energy output from flash lamp 70 reflects from the angularreflector cap 82 and appears at processing surface 88 as if the UVenergy output is emanating from one of three virtual sources, lying intwo distinct planes above the true source in addition to the lightoutput physically emanating from flash lamp 70 itself. A first virtualsource (not shown) will result from the reflection of flash lamp 70 inupper angled piece 76. A second virtual source (not shown) will resultfrom the reflection of the flash lamp 70 in upper angled piece 78.Finally, a third virtual source (not shown) will result from thereflection of flash lamp 70 at the connection of upper angled pieces 76,78 directly above flash lamp 70. The effect is to make each individualUV energy source, e.g. flash lamp 70, behave as if four separate UVenergy sources, although three of the virtual sources lie in one planesomewhat farther from the illuminated plane, while the third virtualsource lies in yet another plane, even farther from the illuminatedplane.

In some embodiments, the angular reflector cell uses only surfaces asflat as mechanically possible with present manufacturing techniques thatmeet at right angles or any other angle that is a multiple of 45degrees. Such angular reflector cell covers may be easier and lessexpensive to construct than, for instance, elliptical surfaces. In someembodiments, upper angled pieces 76, 78 may be oriented at anglesrelative to the horizontal (e.g. relative to the processing surface orline 80), where use of the term “positive” angle indicates an anglemeasured counterclockwise from a relative starting point. Conversely,the term “negative” angle indicates an angle measured clockwise from arelative starting point. For example, as shown in FIG. 4, upper angledpiece 76 may be oriented at a positive angle of 45 degrees as measuredrelative to the horizontal (e.g. line 80). Additionally, upper angledpiece 78 may be oriented at a negative angle of 45 degrees as measuredrelative to the horizontal.

As described above with regard to FIG. 3b , reflecting the UV energyoutput from a flash lamp like flash lamp 70 employs the process ofeffectively multiplying the flash lamp 70 output. That multiplicationmay result from virtual sources created by the reflective surfaces ofangled reflector cap 82 and shroud walls 72, 74. UV energy that emanatesdownward from flash lamp 70, or from the virtual line sources generatedby the angled reflector cap 82, propagates downward to a treatment areadefined by the distance between shroud walls 72, 74 and the width ofprocessing surface 88. UV energy output from flash lamp 70 may alsoreflect once or multiple times off of shroud walls 72, 74 beforereaching the treatment area on processing surface 88. Shroud components(not shown) may be provided perpendicular to the longitudinal axis ofthe flash lamp 70 such that flash lamp 70 appears to virtually extendalong an infinitely long line. Shroud walls 72, 74, placed at either endof the processing surface 88 create a virtual image of the flash lamp 70that appears to extend beyond the location of the shroud walls 72, 74 oneither proximal end of the angled reflector cell. Shroud walls 72, 74may be parallel to the longitudinal axis of flash lamp 70 making theeffectively tripled number of sources act as if they extend for aninfinite distance along both directions perpendicular to the axis.

FIG. 5 is a top view of a system for treating items using a flash lampsystem with a single flash lamp in an angular reflector cell of the typeshown in FIG. 4, according to some embodiments of the presentdisclosure. FIG. 5 shows flash lamp 70, processing surface 88, andshroud walls 72, 73, 74, 75. In some embodiments, shroud walls 72 and 74are substantially parallel to each other, and shroud walls 73 and 75 aresubstantially parallel to each other. Shroud walls 72, 73, 74, 75 arecoupled such that they form a box that defines a treatment area ofprocessing surface 88 to be uniformly illuminated. Shroud walls 72, 73,74, 75 produce a “hall of mirrors” effect, making the flash lamp 70, andthe virtual counterparts created by angled reflection cap 82, appear toextend on into infinity along all directions, so that it will resemblean infinitely long and wide UV energy source that is parallel to theconveyor surface at a fixed vertical distance, as described above. Insome embodiments, shroud walls 72, 74 are coupled to shroud walls 73, 75such that an angle between their connections forms a right angle. Insome embodiments, each of shroud walls 72-75 are perpendicular toprocessing surface 88. Because there will be multiple reflections fromthe mirrored surfaces on the interior of shroud walls 72-75 thereflectivity of the interior of shroud walls 72-75 may be as high aspossible with present manufacturing techniques as required for thewavelength of UV energy emitted by flash lamp 70.

The longer the shroud walls are, the more uniform will be theillumination at the desired plane. However, the longer the walls, themore reflections there will be, each exacting a fraction of the incidentUV energy. Also, the longer the shroud walls, the larger the overalldevice will be. A tradeoff analysis must be made to balance uniformityagainst overall illumination and size. In some embodiments, the shroudshould be at least 2-3 times the cell width “w” for uniformity down tothe single digit percentage range, as described above. Shorter shroudscan be used at the expense of this level of uniformity.

In some embodiments, shroud walls 72-75 may be highly specularreflectors. Shroud walls 72-75 may be highly reflective or textured,they can be made of metal, such as aluminum with a magnesium coating,e.g., a product known as Coilzak, or other covered materials, such as amaterial with a laminate or covering of expanded PTFE. In someembodiments, the interior of angled reflector cap 82 may be textured andnot too reflective. In some embodiments, reflector cell 82 may besymmetric such that the spacing of reflector elements results in virtualimages of the flash lamp that are equidistant from one another, from theperspective of the illuminated processing surface 88. If the symmetry inthose non-limiting embodiments is broken (e.g. different sizedcomponents, improper angles between adjacent components) theillumination of processing surface 88 may not be uniform.

FIG. 6 is a side view of the system for treating items using a flashlamp system with multiple flash lamp angular reflector cells, accordingto some embodiments. FIG. 6 is substantially similar in many ways to thesingle-cell system shown in FIGS. 4 and 5 but differs by combiningmultiple single cells into an implemented system. FIG. 5 shows aplurality of angled reflector cells 85, each including angled reflectorcap 82 made of upper angled pieces 76, 78, and a plurality of flashlamps 70 above a processing surface 88 having a treatment area 87 withwidth “W.” Using the dimensions identified in FIG. 6, for example,multiple flash lamp angular reflector cells 85 may cover N regions withan overall width of the treatment area 87 to be illuminated having awidth W. As shown, each angled reflector cell 85 has a width 89 (notatedas w) calculated as a division of the treatment area 87 by the number ofdesired cells W/N.

In some embodiments, as described in FIG. 4, each angular reflector cell85 may include an angular reflector cap 82. Angular reflector cap 82includes upper angled pieces 76, 78 coupled to form an angle, madepossible by each of upper angled pieces 76, 78 having a length q. Lengthq is calculated such that each of upper angled pieces 76, 78 have alength given by

$q = \frac{w}{\sqrt{2}}$In some embodiments, upper angled pieces 76, 78 are placed at an angleof 45° as measured relative to the angle of the plane to be illuminated.A bottom edge of each of upper angled pieces 76, 78 may align such thatthe plane between two pieces bottom edge meet should be parallel toprocessing surface 88, and an apex of angular reflector cap 82 should bea distance “d” from the flash lamp 70. In some embodiments, lengths q ofboth upper angled pieces 76, 78 are the same. In some embodiments,distance “d” may be calculated as one fourth of width 89, such thatd=w/4. Distance “d” may be above flash lamp 70 in the direction oppositethat of the treatment area 87. In some embodiments, each of the flashlamps 70 may have a corresponding angular reflector cap 82 above it. Insome embodiments, the multiple angular reflector caps 82 may beconstructed using a single piece of material.

FIG. 7 is a side view of a system for treating items using a flash lampsystem with multiple, overlapping circular segment reflector cells,according to some embodiments of the present disclosure. FIG. 7 shows anelliptical reflector cell 90 including an elliptical portion 92 and aparabolic portion 94. The elliptical portion 92 has a verticallyoriented major axis created by the virtual connection of a first focus,f1, and a second focus, f2. A flash lamp 96 is located at first focus,which is above the second focus. The elliptical portion 92 is coupled toparabolic portion 94. Parabolic portion 94 has a focus that is in thesame position as the second elliptical focus, f2, of the ellipticalportion 92. In some embodiments, a window (not shown), like thatdescribed with respect to FIG. 1, may be placed at the bottom of theparabolic portion 94 along a line 98. In some embodiments, the UV energyoutput of flash lamp 96 within elliptical reflector cell 90 is uniformacross a 10× or more coverage area compared to the surface area of flashlamp 96, although there may be some increase along the outer edges of awider coverage area.

In the discussion above, it has been generally assumed that the lampwould be a single cylindrical lamp, but a spiral, helical, or U-shapedlamp could also be used. As with the cylindrical configuration, aminimum of 10× coverage area compared to the area of the outline of thelamp, or even 15×, 20×, or 25× coverage area is desired. The terms“above” and “below,” and “over” and “under,” are used to indicaterelative positioning. A lamp could be provided above or below a conveyorrelative to a gravitational direction, but for purposes here, the lampis considered over or above the conveyor.

The inventions described here thus include reflectors, UV energy systemswith reflectors, methods for manufacturing a reflector, and methods forusing reflectors in a UV energy system. It is to be understood that thedisclosed subject matter is not limited in its application to thedetails of construction and to the arrangements of the components setforth in the following description or illustrated in the drawings. Thedisclosed subject matter is capable of other embodiments and of beingpracticed and carried out in various ways. Also, it is to be understoodthat the phraseology and terminology employed herein are for the purposeof description and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conception,upon which this disclosure is based, may readily be utilized as a basisfor the designing of other structures, methods, and systems for carryingout the several purposes of the disclosed subject matter. It isimportant, therefore, that the claims be regarded as including suchequivalent constructions insofar as they do not depart from the spiritand scope of the disclosed subject matter.

Although the disclosed subject matter has been described and illustratedin the foregoing exemplary embodiments, it is understood that thepresent disclosure has been made only by way of example, and thatnumerous changes in the details of implementation of the disclosedsubject matter may be made without departing from the spirit and scopeof the disclosed subject matter, which is limited only by the claimswhich follow.

The invention claimed is:
 1. A system for providing ultraviolet (UV)energy to items on a processing surface, the system comprising: a lamppositioned over the processing surface to provide UV energy to theprocessing surface; and a reflector cell positioned to cause UV energyemitted from the lamp in a direction away from the processing surface tobe reflected toward the processing surface, the reflector cellincluding: a reflector cap positioned above the lamp, wherein thereflector cap comprises a first elliptical shape with a major axis alonga first line parallel to the processing surface and perpendicular to asecond line from the lamp to the processing surface, the lamp beingpositioned at a first focus of the elliptical shape, and a shroudextending downwardly from the reflector cap toward the conveyor, theshroud having a vertical dimension, a longitudinal dimension, and ahorizontal dimension along the direction of the conveyor, the horizontaldimension and the longitudinal dimension defining a treatment area onthe conveyor, the lamp configured to deliver energy to the treatmentarea, wherein the reflector cap and the shroud are configured such thatthe delivered energy to the processing surface is substantially uniformover the treatment area.
 2. The system of claim 1, wherein the lampincludes at least one flash lamp and the energy in the treatment area issubstantially uniform to within 5%.
 3. The system of claim 2, whereinthe processing surface is defined by a conveyor.
 4. The system of claim1, wherein the reflector cap and the shroud define and enclose atreatment volume, the reflector cap and the shroud having a reflectivematerial along their respective interior surfaces facing the treatmentarea.
 5. The system of claim 1, wherein the reflector cap includes asecond elliptical shape with a major axis along the first line, thesecond elliptical shape having a first focus co-located with the firstfocus of the first elliptical shape, and a second focus of the secondelliptical shape being spaced from the first focus and from a secondfocus of the first elliptical shape along the first line.
 6. The systemof claim 5, wherein the second elliptical shape comprises at least onesection of one or more ellipses.
 7. The system of claim 1, wherein thereflector cap includes a second focus below the first focus, wherein theshroud has a parabolic shape with a focus co-located with the secondfocus of the reflector cap.
 8. The system of claim 1, further comprisinga UV-transmissive window positioned between the lamp and the processingsurface.
 9. The system of claim 1, wherein the first elliptical shapecomprises at least one section of one or more ellipses.
 10. A systemcomprising: at least one ultraviolet (UV) energy lamp positioned above aprocessing surface, wherein the plane of the processing surface definesa first direction, and the direction from the lamp to the processingsurface is a second direction perpendicular to the first direction; anda reflector cell positioned to cause UV energy emitted from the lamp ina direction away from the processing surface to be reflected toward theprocessing surface, the reflector cell including; a reflector cappositioned above the lamp and away from the processing surface, thereflector cap having first and second planar panels that extend awayfrom the processing surface at an angle relative to the second directionand meet at a location above the lamp and form a V-shaped cross section,and a shroud having at least a third panel extending downwardly from thefirst panel toward the conveyor, and a fourth panel extending toward theprocessing surface and parallel to the third side, the lamp providingenergy to the processing surface in a treatment area below the first andsecond sides and bounded by the third and fourth panels.
 11. The systemof claim 10, wherein the lamp includes a flash lamp.
 12. The system ofclaim 10, wherein the reflector cap and the shroud define a treatmentvolume, the reflector cap and the shroud including a reflective materialalong interior surfaces facing the treatment volume.
 13. The system ofclaim 10, wherein the first and second panels intersect such that theV-shape is approximately 90 degrees.
 14. The system of claim 10, whereinthe processing surface includes a conveyor, the system furthercomprising a UV-transmissive window positioned between the lamp and theconveyor.
 15. The system of claim 10, wherein the fourth panel extendsdownwardly from the second panel, such that the first, second, third,and fourth panels define a home plate shape in cross-section.
 16. Thesystem of claim 10, further comprising a second lamp and a secondreflector cap having fifth and sixth planar panels that that extend awayfrom the processing surface at an angle relative to the second directionand meet at a location above the lamp and form a second V-shaped crosssection.
 17. The system of claim 10, wherein the first planar panel andthe second planar panel extending upwardly away from the processingsurface and at about a positive and negative 45 degree angle,respectively, relative to the processing surface, the first and secondplanar panels intersecting above the lamp such that an angle between thefirst planar panel and the second planar panel is approximately 90degrees.
 18. The system of claim 17, wherein the lamp includes a firstlamp and a second lamp spaced apart, wherein the first and second planarpanels extend over the first lamp, the system further comprising a thirdplanar panel and a fourth planar panel, the third planar panel and thefourth planar panel extending upwardly away from the processing surfaceand at about a positive and negative 45 degree angle, respectively,relative to the processing surface, the third and fourth planar panelsintersecting above the second lamp such that an angle between the thirdplanar panel and the fourth planar panel is approximately 90 degrees.19. A system comprising: at least one ultraviolet (UV) energy lamppositioned above a planar processing surface, wherein a direction fromthe lamp to the processing surface is a first direction perpendicular tothe processing surface; and a reflector cell positioned to cause UVenergy emitted from the lamp in a second direction away from theprocessing surface to be reflected toward the processing surface, thereflector cell including, a reflector cap positioned above the lamp andaway from the processing surface, wherein the reflector cap includes afirst elliptical portion that defines a first elliptical shape with amajor axis parallel to the processing surface and perpendicular to thefirst direction, wherein the lamp is located at one focus of the firstelliptical portion, and a shroud extending from the reflector cap towardthe processing surface.
 20. The system of claim 19, further comprising asecond elliptical portion having a major axis co-linear with the majoraxis of the first elliptical portion, wherein the lamp is located at afirst focus of the second elliptical portion, and a second focus of thesecond elliptical portion is spaced from both foci of the firstelliptical portion.
 21. The system of claim 19, wherein the shroudincludes first and second panels that are spaced apart and extend fromthe reflector cap toward the processing surface, the spacing of thefirst and second panels defining a dimension of a treatment area for theUV energy.